Study On The Ore-forming Information And Direction Of Exploration In Xi'anli Iron Deposit

The area of Xi Anli is the part of giant skarn mineral metallogenic belt in the link Pacific Ocean, in the geotectonic structure, it is in the southeast of Lv liang-Tai hang, in the east it approach the basin of Lin Zhou, in the overall it locate in the west of large-scale anticline. In the area Ma jiagou limestone in the middle of Ordovician system widely appear, it thickness is above 500 meters, from south to north, the stratum gradually change newly. In the area ,the Ma jiagou limestone is the most main adjacent that control the iron ore formation and location, it have the good chemistry and the physical condition in the iron separate out and the lithosome compression and expansion localization, it provide advantageous condition that iron ore mineralize in the big area.Based on the predecessor's work, through the careful and thorough geological investigation, acquisition of a great amount of geological information and rock ade ore samples on the ore district and its periphery, applying modern petrology, deposit theory, metallogenic rule and metallogenic prognosis, geochemistry, geophysics theory & method, combining other subjects, also by means of computer to deal with datas and simulate relevant maps, beginning in the ore-forming geological background, comprehensive study has been made on the geology, geophysics and geochemistry of iron deposits.Through the study on geological information that controls the deposits we can see that the scale of deposits and the scale of lithosome depend on existence, the main mining area concentrate in the around of thickness and the high invasion position lithosome, the main ore body produce in the upper contact zone; the second and fourth lothological section of Ma jiagou limestone in the middle of Ordovician system are the most advantageous to the mineralization; the structure belt of north and south is the main mineralization belt, in among it has mined 126 ore bodies; in this area, the magnetite mineralization have related late stage tint neutral diorite body; ore body has the obvious adjacent rock alteration.The research on geochemistry shows that in this area ,in the alteration replacement process, in the ore fluid lead metasonmatic rock the element, no matter they in the alteration belt or outside the alteration belt, they all has the massive increase, alteration are strongly lead the quantity to be more. In alteration replacement process, each kind of element activity order approximately may be: (OH)^-,Na⁺,K⁺,Fe³⁺,Fe²⁺,Mg²⁺,Ca²⁺,Si⁴⁺,Ti⁴⁺,Al³⁺.The alteration intensity of sodium nature metasomatic rock divide into two levels: sodium diorite and albite. The sodium nature replacement and the magnetite origin relation cause the spatial distribution of sodium rock and ore body have an orderly corresponding relation; the Sodium is more stronger and bigger scope, then the ore body scale corresponding is also bigger, in turn is also same. Therefore the intensity and scale of sodium nature metasomatic are important geologic symbol of prospect and appraisal ore body scale.On the base of comprehensive research on ore-forming information of geology, geophysics, geochemistry of iron deposits in Xi'anli, by means o the relation of ore-forming information and iron deposits, marks of comprehensive deposits fingings was put forward and the direction to find iron deposits in Xi'anli, was pointed out.